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In this paper, we classify finite categories with two objects such that one of the endomorphism monoids is a group. We prove that having a group on one side affects the structure of the other endomorphism monoid, and we prove that it is…

Category Theory · Mathematics 2022-10-04 Najwa Ghannoum , Carlos Simpson

We show that the de Jong fundamental group of any non-trivial abelian variety over a complete algebraically closed extension $C/\mathbb{Q}_p$ is non-abelian. Generalizing an argument for $\mathbb{P}^1_C$, we also show that the de Jong…

Algebraic Geometry · Mathematics 2025-12-19 Sean Howe

All possible products of all elements of an odd order finite group are considered. A set of all such products is called as a K-set. A hypothesis of K-set coincidence of any group of an odd order with its commutant is proposed and the…

Group Theory · Mathematics 2007-05-23 V. V. Genk

For an element $g$ of a group $G$, an Engel sink is a subset ${\mathscr E}(g)$ such that for every $x\in G$ all sufficiently long commutators $[...[[x,g],g],\dots ,g]$ belong to ${\mathscr E}(g)$. A~finite group is nilpotent if and only if…

Group Theory · Mathematics 2017-07-14 E. I. Khukhro , P. Shumyatsky

In this paper we show that there is an infinite number of finite groups with two relative subgroup commutativity degrees. Also, we indicate a sufficient condition such that a finite group has at least three relative subgroup commutativity…

Group Theory · Mathematics 2018-01-30 Mihai-Silviu Lazorec , Marius Tărnăuceanu

We present a structural description of finite nilpotent groups of class at most $2$ using a specified number of subdirect and central products of $2$-generated such groups. As a corollary, we show that all of these groups are isomorphic to…

Group Theory · Mathematics 2025-04-08 Dávid R. Szabó

A subgroup $H$ of a finite group $G$ is said to be an NC-subgroup of $G$, if $ H^G N_G (H) =G$, where $H^G$ denotes the normal closure of $H$ in $G$. A finite group $G$ is called a PNC-group, if any subgroup of $G$ is an NC-subgroup of $G$,…

Group Theory · Mathematics 2023-12-27 Shengmin Zhang , Zhencai Shen

We classify all non-degenerate skew-hermitian forms defined over certain local rings, not necessarily commutative, and study some of the fundamental properties of the associated unitary groups, including their orders when the ring in…

Rings and Algebras · Mathematics 2018-04-10 J. Cruickshank , F. Szechtman

We provide an explicit construction for a complete set of orthogonal primitive idempotents of finite group algebras over nilpotent groups. Furthermore, we give a complete set of matrix units in each simple epimorphic image of a finite group…

Representation Theory · Mathematics 2013-02-19 Inneke Van Gelder , Gabriela Olteanu

The goal of this article is to study results and examples concerning finitely presented covers of finitely generated amenable groups. We collect examples of groups $G$ with the following properties: (i) $G$ is finitely generated, (ii) $G$…

Group Theory · Mathematics 2013-05-06 Mustafa Gokhan Benli , Rostislav Grigorchuk , Pierre De La Harpe

Affine difference algebraic groups are a generalization of affine algebraic groups obtained by replacing algebraic equations with algebraic difference equations. We show that the isomorphism theorems from abstract group theory have…

Algebraic Geometry · Mathematics 2020-07-16 Michael Wibmer

A group is metabelian if its commutator subgroup is abelian. For finitely generated metabelian groups, classical commutative algebra, algebraic geometry and geometric group theory, especially the latter two subjects, can be brought to bear…

Group Theory · Mathematics 2012-03-27 Gilbert Baumslag , Roman Mikhailov , Kent E. Orr

We call a finite group irrational if none of its elements is conjugate to a distinct power of itself. We prove that those groups are solvable and describe certain classes of these groups, where the above property is only required for…

Group Theory · Mathematics 2018-07-11 Andreas Bächle , Benjamin Sambale

We study a family of finitely generated residually finite groups. These groups are doubles $F_2*_H F_2$ of a rank-$2$ free group $F_2$ along an infinitely generated subgroup $H$. Varying $H$ yields uncountably many groups up to isomorphism.

Group Theory · Mathematics 2022-07-11 Hip Kuen Chong , Daniel T. Wise

We introduce the concept of quantifying the extent to which a finitely generated group is residually finite. The quantification is carried out for some examples including free groups, the first Grigorchuk group, finitely generated nilpotent…

Group Theory · Mathematics 2010-04-16 Khalid Bou-Rabee

Let $\lambda(G)$ be the maximum number of subgroups in an irredundant covering of a finite group $G$. We prove that the finite groups with $\lambda(G)=|G|-t$, where $t\leq 5$, are solvable, and classify such groups.

Group Theory · Mathematics 2021-03-22 Lifang Wang , Lijian An

We survey the existing parts of a classification of finite groups generated by orthogonal transformations in a finite-dimensional Euclidean space whose fixed point subspace has codimension one or two and extend it to a complete…

Group Theory · Mathematics 2017-11-02 Christian Lange , Marina A. Mikhailova

We show that for any pair of non-trivial finite groups, their coproduct in the category of finite groups is not representable.

Group Theory · Mathematics 2017-05-12 Chris Hall

The authors classify the finite index subgroups of R. Thompson's group $F$. All such groups that are not isomorphic to $F$ are non-split extensions of finite cyclic groups by $F$. The classification describes precisely which finite index…

Group Theory · Mathematics 2007-11-08 Collin Bleak , Bronlyn Wassink

In this note we study a class of finite groups for which the orders of subgroups satisfy a certain inequality. In particular, characterizations of the well-known groups $\mathbb{Z}_2\times\mathbb{Z}_2$ and $S_3$ are obtained.

Group Theory · Mathematics 2016-10-27 Marius Tarnauceanu